Now open Effects-Noise Reduction/Restoration-Noise Reduction (process). You could even apply some compression or hard limiting to bring up the level of subtle background sounds. Now do your basic editing, like cutting out unwanted sections, applying rumble filters, etc. This is under Effects-Amplitude and Compression, either Amplify or Normalize (process). First, process your file with amplification or normalization so the peaks are just below 0dB. Import your selected raw audio file into your audio editor. Noise Reduction Processing an Audio File with the Noise Profile You now have noise profile specific to the equipment you are using. You can add the gain setting if you like as well. Now save that noise print as a file that includes the name of your recorder and microphone pair. Click on the button to Capture Noise Print. Open Effects-Noise Reduction/Restoration-Noise Reduction (process). Now import those files into your audio editing software. You have just recorded nothing but your system noise. You will need to make a different recording for each recorder and microphone set you normally use. Set the gain at the gain levels you would normally use and record for a few minutes. This can be inside an isolated box in the basement or outdoors on a quiet Winter night. Set up your recorder and microphones that you will be using in the quietest place you can find. The first step is to capture noise profiles. WavePad also allows creating and using noise profiles as discussed below and is available for under $100. We will talk about Abobe Audition in particular, but similar processes are available on other programs. The most popular software that have noise reduction features are Adobe Audition, WavePad, Sound Forge, and iZotope RX. It will need processing just like photos need Adobe Lightroom or Photoshop to improve an image for publishing. You will never get a perfect recording straight out of a recorder. It is required software for processing any audio. This software can increase levels, cut, mix, apply effects, and more. Sound editing software is used to process sound files. Ok, so you have a decent recorder and a good microphone and want to get that last bit of system noise out of your recordings. Wildtronics offers the SAAM system that has less than 8dBA of noise. Rode and Lewitt makes some cardioid microphones which have 5dBA noise floors, but are challenging to use outdoors due to humidity sensitivity. Nevaton makes some smaller, 5dBA noise floor mics. Sennhesier makes some omnidirectional mics in that range. There are not many microphones in that range. If you are recording natural soundscapes, you will want the microphone noise floor to be 10dBA or less. How low a noise floor do microphones have to have? A microphone with 16dBA noise floor might be OK if you are using an acoustic amplifier like a parabolic reflector, or recording louder sounds of thunderstorms, creeks, or closeup subjects. When you are recording low levels, microphone self noise starts to become a noticeable issue. Field recording generally involves recording low level sound. So, microphone selection is key to producing a low noise result. The noise from a microphone will always be higher than a good recorder's noise floor. Many low cost, hand held recorders can offer excellent results, even with EINs greater than -126dBA, when paired with products from Wildtronics that have the built-in low noise preamplifiers. The good news is that today there are many very good recorders available at lower prices than ever. The absolute best A/D converters can achieve 140dBA SNR, but the overall SNR will be lower. The specification of interest is the overall SNR (Signal to Noise Ratio). Almost all ADC's are now 24bit depth and some newer recorders are 32bit depth, which is great but a little misleading. The A/D processes the analog signal and converts it to a digital format. The next thing to look for is the A/D specification. Generally, anything less than -126dBA is good (a larger negative number). You could do an internet search to see if others have measured the recorder of interest. This may be a challenge, as many manufacturers do not like listing the spec. A key number to look for in recorders is the EIN (Equivalent Input Noise) specification. Processing very noisy recordings will never result in the best sounding final output. With all the technology available today, there is no excuse to hear microphone hiss in any professional recording.įirst, you really need low noise equipment to start with. Processing and reducing noise should be part of the work flow of editing sounds. From my experience with recording natural soundscapes for over 20 years, I would like to share my technique for eliminating background equipment noise. People have asked us over the years what is the best technique for reducing background noise from audio recordings. Technique for Eliminating Equipment Noise
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